Design and Implementation of a Digital Control IC for Driving Multiple Cold Cathode Fluorescent Lamps

This study designs and develops a digital control integrated circuit (IC) for driving circuits operating multiple cold cathode fluorescent lamps (CCFLs). Inside the IC, two control loops are designed, under synchronized operation frequencies, for a boost regulator and an inverter. The main function of the boost regulator control loop is to supply a steady DC voltage for the inverter. In designing the inverter´s control circuit, an adjustable-frequency adjustable-voltage soft start technique is used to start the lamps. The feedback voltage from the CCFLs can determine if any lamp is abnormal via a proposed lamp abnormality detection circuit. To deal with the equivalent-circuit´s component parameter differences among various manufacturers´ and brands´ piezoelectric transformers (PTs). the inverter´s operation frequency is designed with fine-tunable function in this study. Finally, the proposed design concept was implemented with an actual control IC and a driving circuit for CCFLs.